Inter- and intra-species intercropping of barley cultivars and legume species, as affected by soil phosphorus availability

Abstract

Aims Intercropping can improve plant yields and soil phosphorus (P) use efficiency. This study compares inter-and intra-species intercropping, and determines whether P uptake and shoot biomass accumulation in intercrops are affected by soil P availability. Methods Four barley cultivars (Hordeum vulgare L.) and three legume species (Trifolium subterreneum, Ornithopus sativus and Medicago truncatula) were selected on the basis of their contrasting root exudation and morphological responses to P deficiency. Monocultures and barley-barley and barley-legume intercrops were grown for 6 weeks in a pot trial at very limiting, slightly limiting and excess available soil P. Aboveground biomass and shoot P were measured. Results Barley-legume intercrops had 10-70% greater P accumulation and 0-40% greater biomass than monocultures, with the greatest gains occurring at or below the sub-critical P requirement for barley. No benefit of barley-barley intercropping was observed. The plant combination had no significant effect on biomass and P uptake observed in intercropped treatments.Conclusions Barley-legume intercropping shows promise for sustainable production systems, especially at low soil P. Gains in biomass and P uptake come from inter-rather than intra-species intercropping, indicating that plant diversity resulted in decreased competition between plants for P.

Options for Improved Phosphorus Cycling and Use in Agriculture at the Field and Regional Scales

“…In accompanying greenhouse studies, these authors were able to identify rhizosphere acidification (reduction from pH 5.5 to 3.5) by faba bean and root intermingling between maize and faba bean as the underlying mechanisms allowing for greater P uptake by intercropped maize. Similarly, Darch et al (2018) reported 10 to 70% greater P accumulation in pot-grown intercrops of barley (Hordeum vulgare L.) and green manure legumes relative to the crops grown alone, with greater benefits at lower levels of P fertilization; this was attributed to complementary P use among the intercropped species. In contrast, in a pot study investigating a wheat-faba bean intercrop in a low-P soil, Li et al (2016) found that while P deficiency stimulated root exudation by faba bean, the amount of P mobilization by faba bean was not sufficient to increase P supply to the intercropped wheat.…”

“…The P benefits associated with intercrops tend to be more pronounced when soil‐available Pi is relatively low; however, under extremely low Pi availability, overall productivity of intercrops remains poor (Tang et al, 2016; Darch et al, 2018). Intercropping also risks interspecies competition for P (Simpson et al, 2011).…”

“…Intercropping also risks interspecies competition for P (Simpson et al, 2011). While few studies have compared multiple intercrop combinations, evidence exists that the magnitude of the benefit attributed to intercropping may vary with the component crop species (Tang et al, 2014; Darch et al, 2018) and is not necessarily closely related to the crop's P‐mobilizing capabilities when grown as a monocrop (Darch et al, 2018). …”

“…In crop sequences, decomposition dynamics and their impact on P release from crop residues are of particular interest, as are the relative roles of shoot versus root residues (Kamh et al, 1999; Nuruzzaman et al, 2005; Hallama et al, 2018). In intercrops, the role of crop rooting patterns (i.e., root avoidance vs. intermingling) in creating complementary versus facilitative interactions among crop species requires further investigation, especially under field conditions where roots are less restricted relative to pot studies (Darch et al, 2018). Development of both crop sequences and intercrops that enhance P cycling and crop nutrition also requires consideration of crop‐specific P acquisition mechanisms, the role of the microbial community, and the effects of soil properties, including the amount and form of soil P present.…”

Organic phosphorus: potential solutions for phosphorus security

“…The accepted manuscripts cover an appropriate range of topics related to organic phosphorus. This issue contains papers that we can class as 'reviews' (two papers, George et al 2017 andMenezesBlackburn et al 2017), 'plant centric' (Li et al 2017 andDarch et al 2017), 'soil centric' (three papers, Stahr et al 2017;Missong et al 2017 andSpain et al 2018) 'microbial centric' (two papers Nassal et al 2017 andGaiero et al 2017), 'analytical' (two papers, Adams et al 2017 andWhitfield et al 2017) and 'systems' (two papers Neal et al 2017). An additional historical overview paper has also been published from the Workshop (Haygarth et al 2018).…”